Quadrat. A small field study unit or sample area, usually a square meter or a milliacre in size, established for the purpose of detailed observation. (BCFT.).

Quality, Site. A measure of the relative productive capacity of a site for a particular species. The top height as it varies with age is generally the basis for classification. Syn. Quality class; Quality of locality; Locality class: Site class. (BCFT modif.).

Quincunx. A group of five points, four of which form the corners of a square with the fifth as centre. In planting, an arrangement in which an extra plant is placed in the centre of each square of four plants. (BCFT.).